I have found what I believe is a bug in the radio button part of the button object. When you use the built in conditions for selection a certain button, it doesn't work, but if you use the compare two general values function, it works fine. To test my example, first run the application with the first group activated and the background won't change clicking on the radio buttons. Then, deactivate this group and activate the second one and run it. The buttons should work now.